Re: [PATCH v4 39/54] tests/qtest: boot-serial-test: Close the serial file before starting QEMU

[Marc-André Lureau]

On Tue, Sep 27, 2022 at 3:08 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> From: Bin Meng <bin.meng@windriver.com>
>
> This qtest executable created a serial chardev file to be passed to
> the QEMU executable. The serial file was created by g_file_open_tmp(),
> which internally opens the file with FILE_SHARE_WRITE security attribute
> on Windows. Based on [1], there is only one case that allows the first
> call to CreateFile() with GENERIC_READ & FILE_SHARE_WRITE, and second
> call to CreateFile() with GENERIC_WRITE & FILE_SHARE_READ. All other
> combinations require FILE_SHARE_WRITE in the second call. But there is
> no way for the second call (in this case the QEMU executable) to know
> what combination was passed to the first call, unless FILE_SHARE_WRITE
> is passed to the second call.
>
> Two processes shouldn't share the same file for writing with a chardev.
> Let's close the serial file before starting QEMU.
>
> [1] 
> https://docs.microsoft.com/en-us/windows/win32/fileio/creating-and-opening-files
>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



> ---
>
> Changes in v4:
> - New patch: "tests/qtest: boot-serial-test: Close the serial file before 
> starting QEMU"
>
>  tests/qtest/boot-serial-test.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/tests/qtest/boot-serial-test.c b/tests/qtest/boot-serial-test.c
> index 72310ba30e..b216519b62 100644
> --- a/tests/qtest/boot-serial-test.c
> +++ b/tests/qtest/boot-serial-test.c
> @@ -233,6 +233,7 @@ static void test_machine(const void *data)
>
>      ser_fd = g_file_open_tmp("qtest-boot-serial-sXXXXXX", &serialtmp, NULL);
>      g_assert(ser_fd != -1);
> +    close(ser_fd);
>
>      if (test->kernel) {
>          code = test->kernel;
> @@ -266,6 +267,8 @@ static void test_machine(const void *data)
>          unlink(codetmp);
>      }
>
> +    ser_fd = open(serialtmp, O_RDONLY);
> +    g_assert(ser_fd != -1);
>      if (!check_guest_output(qts, test, ser_fd)) {
>          g_error("Failed to find expected string. Please check '%s'",
>                  serialtmp);
> --
> 2.34.1
>